An uncut integrated circuit formed in a semiconductor wafer, an integrated circuit cut into chip-like sections, and an integrated circuit (i.e., a device under testing) such as an integrated circuit cut into chip-like sections and packaged or molded are subjected to a test as to whether or not they provide performance as per specification.
A probe card used in such a test generally comprises a probe base plate having a plurality of signal paths, i.e., electrically-conductive paths, and a plurality of contacts arranged on one face of the probe base plate and electrically connected to the conductive paths.
As such a probe base plate are used a wiring board made of glass epoxy resin, a ceramic base plate made of ceramic, a flexible multilayer wiring board made of an electrically insulated resin such as polyimide resin, or a base plate for combined use with the flexible multilayer wiring board disposed on the underside of the ceramic base plate.
Currently, testing of an integrated circuit under high temperature is carried out. In this case, an integrated circuit is heated to a given temperature by a heating element provided in a stage where the integrated circuit is disposed, whereby a probe base plate where contacts are disposed is also heated upon receipt of the heat from the stage and the integrated circuit. As a result, the integrated circuit and the probe base plate are thermally expanded.
If, however, an amount of thermal expansion of the integrated circuit and that of the probe base plate are different, a relative physical relation between an electrode of the integrated circuit and a tip of the contact changes, so that there unavoidably may exist some contacts whose tips are not pressed against the electrodes of the integrated circuit.
Thus, a test apparatus is proposed wherein a heating element disposed within a probe base plate is heated to heat the probe base plate, thereby adjusting the temperature of the probe base plate (Japanese Patent Appln. Public Disclosure No. 4-359445), which is incorporated by reference.
However, in the test apparatus as described in Japanese Patent Appln. Public Disclosure No. 4-359445, only a single metal layer is provided in the probe base plate as a heating element. Thus, it takes a long time for the probe card, particularly a ceramic base plate, to be heated to a given temperature, so that its operating efficiency is low.
For instance, in a test apparatus to move a stage relative to the probe card every time a test of wafer is finished, the probe card is exposed to ambient temperature whenever the stage is separated from the probe card, so that the temperature of the probe card lowers.
In an apparatus to test multiple wafers by dividing them into lots and to test per lot, each lot including a plurality of wafers, a probe card is exposed to ambient temperature not only each time a test of one wafer is finished but also every time a stage is moved to replace the wafers per lot. In such an apparatus, the temperature of the probe base plate lowers while the probe card is exposed to ambient temperature.
In view of the above, in a conventional test apparatus, the temperature of a probe card should be raised again to a given one for the subsequent wafer test. In the conventional test apparatus, however, it takes a long time to raise the lowered temperature of the probe card again to a given temperature, so that the test efficiency is remarkably low.
Also, in the conventional test apparatus, if power for heating is supplied to a heater though the test signals are fed to an integrated circuit, the test signals are greatly affected by the power for heating, so that accurate test results may be obtainable.